IN the exhilarating, anything-is-possible days of 1998 to 2001, Kozmo.com offered an online store with a quick delivery service in a number of American cities. "Free delivery in under an hour" was its motto.
Kozmo would perish, but some online merchants and their delivery partners are inching back toward that shining vision. Though they aren't promising free delivery within an hour, they are trying out same-day service for a fee. And in doing so, they are addressing the asymmetry that has bedeviled online purchases of physical goods since Kozmo's demise: it takes mere seconds to find and buy goods on the Web, but often several days for them to arrive at the doorstep.
Could the wait again be shortened to just an hour? That remains to be seen.
The United States Postal Service will experiment with same-day delivery of online orders in San Francisco. It sees the new option, called Metro Post, as a way to put its delivery infrastructure to fuller use while developing a new source of revenue -- a matter of pressing importance as the service's finances go from bad to worse.
The Postal Service proposes once-a-day pickup of goods ordered online from participating retailers in the city before 2 p.m. and delivery to homes between 4 and 8 p.m.
John G. Friess, a Postal Service spokesman, says the packages won't go through the normal processing centers, but will instead be passed directly between the Postal Service workers who pick them up and deliver them.
"This will be a new experience," Mr. Friess says, "having a uniformed Postal Service employee knocking on your front door at this hour, delivering the package that you had ordered earlier in the day."
A flat rate will be charged for all packages up to 25 pounds, he says, but the price has not been announced and may be adjusted as the trial proceeds.
With its fleets of trucks, United Parcel Service also has the delivery infrastructure for same-city, same-day service. But for now, the company is not set up to do both pickup and delivery in the same day, in the same city, at a modest price.
I used the online U.P.S. pricing guide to find the cost of having a one-pound book picked up at a San Francisco bookstore at 2 p.m. and delivered to a home address a mile and a half away by 8 p.m. the same day. This required U.P.S.'s "Express Critical" service, and the company estimated the cost at $226.46.
If U.P.S. decided it wanted to enter the intracity delivery business in a serious way, it could no doubt offer much more attractive pricing. In fact, it would seem positioned to offer a lower price than the Postal Service, whose operational decisions must be approved by the Postal Regulatory Commission. The Postal Service's filing with the commission to try out Metro Post is timorous in tone and lists self-applied hobbles. For example, the service says it will enlist 10 or fewer companies for the trial and limit the volume to 200 packages a day, at least until it can "further test its operational capabilities."
The big online retailers are running their own experiments with same-day delivery in some markets.
Last month, Wal-Mart announced that it had begun same-day delivery of online orders in a handful of cities. A check last week of the price of two-hour delivery windows in San Francisco showed flat fees of $6 to $7. (The minimum order is $45.) Amazon also offers a same-day delivery option in 10 markets. In addition to a delivery charge of $8.99 for all orders other than gift cards, it adds a charge of 99 cents for each item in the order.
Very fast delivery of online purchases can be found in Lower Manhattan, the area served by UrbanFetch, which offers 10,000 products online that will be delivered within an hour. The speed is the same as Kozmo's -- in fact, the company was founded in 2005 by Chris Siragusa, who was chief technology officer at Kozmo -- but the selection of goods is far larger.
Customers must live within an eight-square-mile service area, and all deliveries are carried by bicycle. There is no delivery fee for orders of more than $100; a $4.95 fee is charged for smaller orders.
When Mr. Siragusa set out to build an online store with home delivery -- originally called MaxDelivery -- he did not plan to match Kozmo's one-hour promise. With friends and family, he first tried a service in which the ordering was done earlier in the day and the deliveries in the evening. But he concluded that late-in-the-day delivery was not compelling to customers. "It was still more convenient to walk to the store yourself," he said.
UrbanFetch's fast delivery is possible because its goods are physically close to its customers in a densely packed city. In other places, online customers must be a bit more patient, as Son of Kozmo is not in sight.
Randall Stross is an author based in Silicon Valley and a professor of business at San Jose State University. E-mail: firstname.lastname@example.org.
This article originally appeared in The New York Times.